Search

The effect of microwave pretreatment and moisture levels of Camelina sativa seeds on the quality of extracted oil by cold press was investigated. The seed moistures were adjusted to 2.5%, 5.0%, 7.5%, and 10.0% and pretreated with microwaves for 0, 1, 2, and 3 min. Microwave pretreatment (3 min) of the seeds with 2.5% moisture increased the oil extraction yield by ∼11% compared to the control sample. The highest amount of acidity (0.564 g FFA·g−1 oil), peroxide value (2.4 meq O2·kg−1 oil), carotenoid (5.26 mg·kg−1 oil), and browning index (0.710) were found in the oil extracted from seeds with 10% moisture and 3 min microwave pretreatment. The total phenolic compound was increased by microwave pretreatment but was mitigated by the seed moisture content, and the highest amount (208.24 mg caffeic acid·100 g−1 oil) was observed at 3 min microwave pretreatment of the seeds with 2.5% moisture. Chlorophyll content decreased by both microwave pretreatment and seed moisture content in camelina oil. Generally, the fatty acid composition of the extracted oils was not affected by the seed pretreatments. In conclusion, pretreatment of the camelina seeds before oil extraction is suggested to obtain a high oil extraction yield with a good quality oil.

Due to high antimicrobial activity against numerous microorganisms, silver nanoparticles (AgNPs) are being utilized in various areas. Microwave-accelerated AgNPs synthesis using Corylus avellana leaf extract was evaluated. Based on randomly central composite design, 13 mixture solutions containing different amounts of the prepared extract (0.10–0.90 mL) and 1 mM silver nitrate solution (15–25 mL) were prepared and exposed to microwave irradiation for 180 s. Response surface methodology was utilized to evaluate the effects of the two independent variables on particle size and concentration of the synthesized AgNPs, as manifested in the place of broad emission peak (λ max) and its absorbance unit, respectively. Fourier transform infrared spectroscopy analysis indicated that the two hydroxyl and carboxylic acid functional groups with reducing activity existed in the prepared extract. Dynamic light scattering and transmission electron microscopy analyses revealed that the formed spherical AgNPs using optimum amounts of C. avellana leaf extract (0.9 mL) and 1 mM silver nitrate solution (25 mL) had minimum particle size (103.5 nm) and polydispersity index (PDI) (0.209), and maximum concentration (140 ppm) and zeta potential (−21.8 mV). Results indicated that the formed AgNPs had high fungicidal effects against the spoiled fungi of Colletotrichum coccodes and Penicillium digitatum.

In order to alter the solubility and bioavailability of various functional lipids and plant essential oils (EOs), it is possible to prepare their oil in water (O/W) nanoemulsions. Thyme O/W nanoemulsions were prepared under subcritical water conditions (at 120°C and pressure of 1.5 atm for 2 h), using Tween 20, Tween 80, saponin, Arabic gum, xanthan gum, and sodium caseinate as emulsifiers. Results indicated that nanoemulsions with minimum mean droplet size of 11.5 and 12.6 nm were produced using Tween 20 and 80, respectively. Moreover, nanoemulsions with minimum polydispersity index (0.139) and maximum mean value of zeta potential (−24.5 mV) were provided utilizing xanthan gum and saponin, respectively. Results also revealed that the prepared nanoemulsions using saponin had maximum antioxidant activity based on percentage of scavenging ability (40.6%) and bactericidal effects against Streptococcus mutans as manifested in the formed clear zone (diameter of 21 mm). Morphological assessment of all the prepared nanoemulsions demonstrated that spherical thyme nanodroplets were formed in the colloidal solutions which revealed that all the prepared nanoemulsions had high thermodynamic stability due to the minimum surface energy level of the formed nanodroplets. This can increase applications of the prepared thyme O/W nanoemulsions in the aqueous food and pharmaceutical formulations.

Silver nanoparticles (AgNPs) were synthesized using Aloe vera leaf extract as both reducing and stabilizing agents via microwave irradiation method. The effects of the microwave exposure time and the amount of AgNO3 solution on the mean particle size and concentration of the synthesized AgNPs solution were investigated using response surface methodology. The synthesized AgNPs were characterized by transmission electron microscopy, UV-Vis spectroscopy, and dynamic light scattering. Well-dispersed and spherically fabricated AgNPs with mean particle size (46 nm) and maximum concentration (64 ppm) and zeta potential (+15.5 mV), were obtained at optimal synthesis conditions, using 9 ml of AgNO3 (1 mm) and 0.1 ml of Aloe vera extract during microwave exposure time of 360 s. The antibacterial activity of the synthesized AgNPs was tested using Escherichia coli and Staphylococcus aureus bacteria and the obtained results indicated their significant inhibitory effects against these two Gram-negative and Gram-positive bacteria.